A heat exchanger including a core portion that exchanges heat and a header portion mounted on the core portion is known in general. A heat exchanger like this is disclosed in Japanese Patent Laying-Open No. 2011-80750 and Japanese Utility Model Laying-Open No. 6-65775, for example.
In Japanese Patent Laying-Open No. 2011-80750 and Japanese Utility Model Laying-Open No. 6-65775, there is disclosed a heat exchanger including a heat exchange block (core portion) that exchanges heat, a header portion for supplying a fluid to the heat exchange block (core portion) or discharging the fluid from the heat exchange block (core portion), and an intermediate member (joint plate) made of metal and provided between the heat exchange block (core portion) and the header portion. In this heat exchanger, the intermediate member (joint plate) made of metal is formed of a rectangular frame body (a frame body having right-angled corners in a plan view). One side of the intermediate member (joint plate) is brazed or welded to the heat exchange block (core portion), and the other side of the intermediate member is welded to the header portion. The heat exchange block (core portion) has a rectangular parallelepiped shape.